Expressions in cardiology

Archive for February, 2010

Cardiology is among the top medical specialty in the current era. It deserves this special status as it is probably the a specialty which is based on maximum scientific evidence and involves , the most advanced diagnostic and treatment modalities.

As on today , a cardiologist can deliver a stent anywhere along the coronary tree and even implant a valve percutaneously . A surgeon can put multiple grafts in a beating heart with a patient totally awake !

A person can live with an artificial heart for months and a cadaver heart can give fresh lease of life to a terminal heart failure patient .

Why such a glorious filed of cardiology should often evoke a pessimistic reaction in the minds of public and media ?

This is because for a simple reason , in the name of technology , we tend to indulge in scientific excesses.

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We generally believe drugs and devices are prescribed by physicians with strong scientific basis .Unfortunately it is not true in many instances. A drug which is approved for one disease is assumed to be useful in a similar disease (But not tested in clinical trials ) and it becomes an unapproved indication .This is often termed as off label use (A decent terminology for unscientific usage !) .But ,there are pros and cons to this type of physician behavior .

Pros

The best example is the role of sildanafil in pulmonary arterial hypertension(PAH) . A drug which was introduced for erectile dysfunction , was found to very useful in regressing pulmonary arteriolar pressure (Mistaking pulmonary arteriole for penile vasculature !?) . A new therapeutic concept was born for a hither to difficult problem of PAH. This successful discovery was attributed to off label usage of a drug .

Cons

But this is a rare success story of off label therapy. In real world , we tend to overuse this in many situations and harm is anticipated.

Drug eluting stents was used extensively in off label situation ( Acute MI in a thrombotic milieu, very small vessels , in close proximity to bare metal etc all these are non label or off label use of coronary stents which resulted in many deaths )

Who gave the freedom and liberty for the physicians to use a drug or device off label ?

No body gave it , we assumed , we have it .

When somebody uses a drug for an unapproved indication is it not unscientific and guideline violation ?

It is a violation , but we can afford to do it because every body does so !

Is there any scientific body to sanction and desanction off label usage ?

Common sense would indicate medical care is meant for the sick and ill . Relieving the mankind from all those suffering with a healing hand has made the medical profession noble and sacred .Medical science grew with this sole aim many centuries ago .Some times we succeeded and many times we failed and the journey is continuing .

In those days ,scientists were dedicated , inventions were genuine and were driven by a need to conquer a diseases .Some where along the line, (May be in the last 2-3 decades?) our quest for money power exceeded commonsense . Commerce entered every walk of life and medical science became the biggest causality.

The purpose of noble profession was forgotten . Simultaneously public awareness and quality if life vastly improved in many of the developed countries . So the traditional illnesses either disappeared or reduced to a great extent . Then came the life style diseases.The cost of treating an illness spiraled too much especially in the scientifically advanced countries . What was perceived as great health care system became the most ridiculed health system in the planet ?

Why ? The simplest answer to this q is

In the name of science and modernity , medical treatment was glorified beyond the level it deserves , and hence the cost of treatment is kept at artificially & foolishly high (This often involves diagnostic exploration of human body with modern gadgets without any meaningful purpose ) .

ie , In a nutshell of modern medicine is often a medical mirage than a miracle . We know , the chances of success as we try to chase it. If we think the world is waking on this issue .

We are in for a surprise ! Even as every one is asking for outcome analysis in modern health care

more and more countries just imitate the failed ( Scientific and moral failure ) western models of health care .

When major illness are reducing in a society what will the health care providers do ?

When the patient input into a top hospital reduces , the MBAs in them plan strategies to bring increase the bed occupancy rate and maintain patient parity.

If sufficient patients are not there in a community what shall we do ?

Create more patients

Creating new patients is a too dangerous game , what shall we do ?

In the name of preventive screening let us label normal persons as patients .

How to do it ?

The following examples are personal observation made in huge city of educated elite in a developing country . Excuse me if it offends a few . . .

Define, redefine all criteria that define the disease (There are

Make, 130/85mmhg of blood pressure as pre hypertension and make them visit our HT clinic every month.

In the name of risk stratification do CRP, Micro HDL , Apo a etc and catch them for primary risk reduction for a non existing illness

Let us label all the age related bone loss as deadly osteoporosis and do bone graft.

Let us call the occasional post dinner stiff stomach as non ulcer dyspepsia and insert a endoscope into the patient tummy .

Do a 64slice CT in a master health check and convert many of the healthy normals into carriers soft coronary plaques.

Do a ultra sound scan in every one who takes alcohol and give our brains a temptation to label the normal fatty streaks as infiltrative fat disorder .

Do routine pelvic scan and detect sub clinical fibroid uterus as potentially malignant and post them for hysterectomy on the next operation day.

Convert all healthy women as a potential cervical cancer and administer herpes vaccine and help the vaccine company share move up in wall street !

Finally ,screen all our playful kids for learning disability and label them as slow attention deficit disorder and make their life permanently miserable .

The list is endless . . .

Final message

We are in a era , where even a simple illness ( common cold ? ) can be converted into a billion dollar industry . ( Are you aware of H1N1 fiasco , The role of WHO and mystery labeling of pandemic !)

While the above misadventure with scientific excesses goes on merrily , lest we forget , millions of children and adults suffer in misery for want of live saving investigations and drugs in any country .

When a person with a head injury dies due a missed subdural hematoma for want of CT scan in one hospital , ” in the adjacent hospital” a wealthy and healthy man ( who got admitted for master health check up ) undergoes a series of scans all over the body even as he is watching the satellite TV in the comfort of a five star suite !

God will never forgive the noble professionals if they are part of this negative health care forces

Finally ending with a very positive note !

The new initiative by Obama , ” Health care for the uninsured ” is to be welcomed as great move and will do a world of good .

But , our only request to WHO ( or related bodies ) is to create a forum or authority to impeach all fancy diseases from the medical literature !

The same channels , that create the deadly prolonged QT interval by delaying the repolarisation in the heart is responsible in the for the deafness as it interfere with inner ear

Mechanotransduction of sound into neural signals .

For proper auditory function , the cochlear hair cells needs a continuous flow of endolymph which maintain a voltage gradient for nerve signal transmission .The lymph secretion is is regulated by potassium channels KCNQ1 and KCNE1 . Mutations of this gene impairs the K + content of the endolymph. It results in a compromised endocochlear potential (Difference between peri lymph and endolymph potenial ) .This result in irreversible deafness .

A loud first heart sound (S 1) which is heard intermittently in patients with complete heart block (CHB) is often referred to as cannon sound .

What is the mechanism of loud S1 in CHB ?

We know , the intensity of S 1 is mainly determined by the relative position of mitral leaflet (To be precise, the anterior mitral leaflet(AML) ) at the onset of systole. We also know the PR interval has an intricate relationship to mitral leaflet position .

The shorter it is , wider the leaflet separation and a longer PR interval makes a mitral leaflet assume a almost closed position by the time the ventricle contracts.this happens because a long drawn PR interval fills the ventricle more completely and LVEDV reaches the maximal levels and LV blood column lifts up the mitral leaflets , and hence the LV contraction which follows does not close it with a bang. In a short PR interval the opposite happens and hence a loud S1 .

In CHB we have variety of PR intervals ranging between very short to long ( falling just before the qrs complex) It is not difficult to understand this , as P waves are totally dissociated with the QRS complex in CHB.In fact p waves have a liberty to fall any where in the ECG tracing , some call this as marching through the qrs complex !.

Hence typically the S1 is variable in intensity , varying between loud to soft. When P wave falls just behind a QRS complex , it generates a very loud S 1 that is called cannon sound .This happens intermittently.

Cannon wave

This is entirely different phenomenon except that it shares the word cannon . Cannon a wave is a visual finding on the jugular venous pulse.(JVP) .It is a systolic event . It is also seen in CHB as like a cannon sound

This is a giant a wave in JVP when the right atrium contracts against a closed tricuspid valve. In physiological situations atrium contracts with an open AV valves , so that ventricle gets filled . So atrial contraction does not does not cause any reflux of blood back into vena cava.

But, when the atrium contracts and finds , the AV valve closed there is no other option for the incoming blood to reflux back into the neck veins. This is seen as giant a waves called as cannon ” a “waves

In fact , it is a non- relationship. Though , both the sound and wave can occur in a given patient with CHB , they can not occur simultaneously .This is because , for cannon sounds to occur the P wave has to fall before QRS and for cannon waves to occur the p waves must fall after QRS ie with QT interval .

Clinical significance of cannon wave

Complete heart block is the most common situation for cannon waves to occur.

Ironically ,the VVI pacemaker which is used to treat CHB does not prevent the cannon waves , and atrial contractions continue to occur at random , causing various degrees of intermittent venous reflux into the veins .This may produce, worrisome venous palpitation in some (Usually settles down after few weeks !)

We hoped so , it does in fact . But, it really happens only if the A sense V pace mode . A pace V pace mode with programmed PR interval is not a realiable way to produce AV synchrony. It is common , many of the DDD pacemakers fall back to VVI mode either intentionally or by mode switching for various reasons.